Direct iron ore reduction



DBC. 20, W, E. TREN-r DIR-ECT IRON oR: REDUCTION Filed Deo. A3. 1930 2 Sheets-Sheet l aww/nto@ Wa/ferlfenf w, @f 2,74. 9%

Dec- 20 1932. w. E. TRENT 391850 DIRECT IRON ORE REDUCTIN Filed Deor. 1930 2 Sheets-8het .2

WIJ/Uni @e L )if J? Patented Dec. 20, 1932 UNITED STATES PATENT OFFICE 'WALTER EDW'IN TRENT, OF NEW YORK, N. Y., ASSIGNOR T0 TRENT PROCESS CORPORA- TION, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE DIRECT IRONA ORE REDUCTION My invention relates tothe direct reduction of iron ore and more particularly comprises a process wherein bituminous coal is distilled to the stage of low temperature coke and iron ore added to the coke while the latter still retains a high hydrogen content, the mixture heated in the presence of hydrogen and carbon monoxide formed in the process to reduce the ore, and the reduced ore or sponge iron separated from the gangue, ash, and unconsumed carbon; all as hereinafter fully pointed out and claimed.

For a more detailed understanding of my invention, the process will be described in connection with the accompanying drawings wherein Figs. 1 and 1a represent a more or` less diagramatic side elevational view, partly in vertical section, lof an apparatus in which the process may be carried out.

Referring to the drawings, at 1 is shown a vertical retort comprising heating compartment 2 and vertically spaced communicating heating tubes 3. Each of the tubes 3 is provided with a screw conveyor 4 driven by any suitable means and adapted to move solid material back and forth across the retort during its descent through the latter. Heating gases are generated at the ovens or burners 5 and supplied to chamber 6 in the lower portion of the retort through pipes 7 and manifold 8. The heating gases circulate around tubes 3 and are discharged from the ,upper portion of the retort through outlet 9. A coal hopper 10 supplies earbonaceous material to the uppermost tube 3 while a hopper 11 is adapted to feed iron ore into an intermediate heatin tube 1 2 positioned a substantial distance rom the top and bottom of the retort. The upper tubes of the retort are provided with vapor and gas outlets 13 which communicate with manifold 14 leading to condenser 15 and gas purifier 16. Condensate formed in the condenser is collected in receiver 17. The gases are discharged from purifier 16 through pipe 18 by means of fan 19 and are collected in gas holder 20. Gases may be supplied from gasometer 2O to burners 5 through pipe 21.

The intermediate heating tube 12 to which the ore is supplied is provided with a gas outlet 22 leading to condenser 23 and purifier 24, a receiver 25 being provided for condensate. The gases are drawn from purifier 24 through pipe 26 by means of fan or blower 27 and are thence supplied to gas holder 28. A conduit 29 is provided for supplying gases from gasometer 28 to the lowermost tube of the retort. An air supply pipe 30 is also connected into the lower discharge portion of the retort.

The solid residue discharges from the retort onto an endless conveyor 31 by which it is carried to an amalgamator 32. The amalgamator is divided into a plurality of compartments by means of baflies 33, each compartment being provided with an agitator 34 driven by any suitable means 35. The amalgamator discharges into separator 36 and the heavier materials are removed from the bottom of the latter by means of drageseparator 37. The amalgam overflows separator 36 and is carried by means of endless conveyor 38 to hopper 10.

A pipe 39 communicates between gas holder 28 and burners 5 for supplying gas from the former to the latter. The piping system is' provided with valves wherever desired as shown on the drawings.

Describing now the process with reference to the illustrated apparatus, bituminous coal, admixed with amalgam obtained as hereinafter described, is fed to uppermost tube 3 and is moved downwardly throu h the retort by means of conveyors 4. In descending through the retort the material is progressively heated indirectly by the gases supplied from burners 5 to chamber 6 and passing around the tubes to the outlet 9. The heating is such that the carbonaceous material, when arriving at intermediate tube 12, is at the stage of low temperature coke but still containing a high hydrogen volatile content. In the case of bituminous coal, a temperature of between 600 Fnand 12600 F. is adequate for this purpose. Hydrocarbon vapors and gases evolved from the carbonaceous materials are removed from the upper portion of the retort through pipes 13, the vapors condensed in condenser 15 and the condensate collected in receiver 17, the gases purified in any known and suitable manner in purifier lband then collected in gasometer 20.

pon arriving at intermediate tube l2, the

low temperature coke having a high hydrogen content, isvmixed With pulverized iron ore supplied from hopper 11. The coke and ore may be mixed in substantially equal proportions but it Will, of course, be understood that this ratio may be varied. The mixture of coke and ore now descends through the hotter zones of the retort wherein the teinperatures are such as to adequately reduce the ore.- Such temperatures may range between 1000o F. and 3000 F. The volatiles removed from the coke and the carbon monoxide gas, formed by reaction between the hot coke and the oxygen of the ore, are removed from thejreduction section of the retort through the outlet 22. These gases consist principally of hydrogen and carbon monoxide and are kept separate'from the gases and vapors removed from the upper distilling section of the retort. The gases issuing through pipe 22 are cooled in condenser 23 to separate any condensible vapors present therein and the gases purified in any known manner in purifier 24, the purification being especially directed to the removal of sulphur. The purlfied gases are collected in gas holder 28 and portions thereof continuously recirculated through pipe 29 to the lowermost tube of the retort to flow upwardly therethrough countercurrent to the descending ore and coke. As stated, these purified gases consist essentially of hydrogen and carbon monoxide, both of which are strong reducing a ents when in contact. with the hot mixture oiron oxide and coke. By introducing these gases near the discharge point of the retort, they exert a strong cooling action on the hot charge thereby utilizing a large portion of the sensible heat of the charge upon completion of the reduction, this heat being transmitted to the solids descending in the retort.

During the operation limited quantities of air are introduced to the retort through pipe 30 to eiect incomplete combustion of the hot coke to thereby secure internal heating and to form additional quantities of carbon monoxide. External heating of the tubes 3 may be effected by combustion of gases from gasometers 20 and 28 in the burners 5, these gases being supplied through pipes 21 and 39.

The reduced ore, gangue, unconsumed carbon and coal ash are discharged from the retort onto conveyor 31 and transferred to amal amator 32. The solids are here agitated with light hydrocarbon oil in a body of Water in accordance with the purifying process of my prior Patent No. 1,420,164, although any other suitable separation process may be resorted to. By virtue of the amalgamation the solids are separated into three classes of material, namely, reduced iron ore or sponge iron, gangue and ash, and carbon, the latter amalgamating with the oil. The reduced metal gravitates to the bottom of separator 36 and is Withdrawn therefrom by means of drag-separator 37 for collection. The carbon-oil amalgam is separated from the gangue and water and returned to hopper 10 by endless conveyor 38.' Upon return to the retort the amalgam is freed of oil and the carbon utilized for the reduction of further quantities of ore.

l.Although I have described my invention with considerable particularity it is to be understood that various changes and modiiications may be made Without departing from the spirit and scope of the invention as defined in the appended claims.

Having described my invention, I claim 1. A process for the direct reduction of iron ore, which comprises mixing the ore With low temperature coke having a substantial volatile hydrogen content7 heating the mixture to reduction temperature in an atmosphere of hydrogen and carbon monoxide, separating the reduced iron from Vthe gangue and excess coke, and recycling through the reduction zone gases evolved therein `to provide said atmosphere.

2. A process which comprises distilling coal to the stage of low temperature coke Without completely de-volatilizing the Same and removing and condensing evolved vapors, then mixing iron ore with the coke 'and subjecting the mixture to reduction con-- ditions, removing and collecting resultant gases independently of said vapors, and recycling portions of said gases into Contact with the mixture of ore and coke undergo ing reduction.

3. A process which comprises distilling coal to the stage of low temperature coke Without complete de-volatilizing the same and removing and condensing evolved vapors, then mixing iron ore with the coke and subjecting the mixture to reduction conditions, removing and collecting resultant gases independently of said vapors, and recycling portions of said gases into contact with the mixture of ore and coke undergoing reduction, separating the unconsumed coke from the reduced ore by amalgamation With hydrocarbon oil` and returning the resultant amalgam to the coal being distilled.

4. A process as defined in claim 2 further characterized in that the coke in said mixture is incompletely burned during the reduction of the ore.

5. A process which comprises continuously advancing coal through a distillation zone and `distilling the same therein to the stage of low temperature coke, removing and condensing the vapors evolved in said zone, mixing iron`ore With the coke before the latter has been completely deprived of volatiles and continuously advancing the resultant mixture through a reduction zone, reducing the orc in said reduction zone and removing resultant gases, and recycling portions of said gases to the reduction zone to flow countercurrent to the mixture advancing therethrough.

A process which comprises continuously advancing coal through a distillation zone and distilling the same therein to the stage of low temperature coke, removing and condensing the vapors evolved in said zone, mixing iron ore with the coke before the latter has been completely deprived of volatiles and continuously advancing the resultant mixture through a reduction zone, reducing the ore in said reduction zone and removing resultant gases, and recycling portions of said gases to the reduction zoneto flow'countercurrent to the mixture advancing therethrough, separating the reduced ore from unconsunied coke by amalgamation of the latter with hydrocarbon oil,`and returningthe amalgam thus formed to said. distillationzone.

7. A process which comprises'continuously advancing coal through a distillation zone and distilling the same therein to the stage of low temperature coke, removing and'condensing the vapors evolved in said zone, mixing iron ore with the coke before the latter has` been completely deprived of volatiles, and continuously advancing the resultant mixture through a reduction zone, reducing the ore in said reduction zone and removing resultant gases, introducing air adjacent the discharge portion of said reduction zone to incompletely burn the coke, and recycling portions of said gases to the reduction zone to iiovv`` countercurrent to the mixture advancing therethrough. A

8. A process which comprises continuously portion of the heatin zone, then adding the f ore to the thus treate carbonaceous material in an intermediate portion of the heating zone, and passing the resultant mixture through the remainder of the heating zone wherein it is subjected to increased temperatures adequate to effect substantial reduction of the ore. l,

10. The process asv defined in claim 9 further characterized in that the earbonaceous material still contains volatiles Where the ore is added thereto in the intermediate portion of the heating zone. l

l1. A process which comprises distilling carbonaeeous material in a distillation zone to remove volatiles therefrom, adding ore to the thus distilled material and heating the resultant mixture to effect substantial reduction of the ore, separating the reduced ore from unconsumed carbonaceous matrial by amalgamation of the latter with oil, and introducing resultant amalgam to said distillation zone. Y

In testimony whereof I aiix my si ature.

'WALTER EDWIN TR NT.

advancing coal through a distillation zone and distilling the same therein to the stage of low temperature coke, removing and condensing the vapors evolved in said zom, mixing iron ore with the coke before the latter has been completely deprived of volatiles, and continuously advancing the resultant mixture through a reduction zone, reducing the ore in said reduction zone and removing resultant gases, `introducing air adjacent the discharge portion of said reductionzone to incompletely burn the coke, recycling portions lof said gases to the reduction zone to flow countercurrent to the mixture advancing therethrough, separating the reduced ore from unconsumed coke by amalgamation of the latter with hydrocarbon oil, and returning theamalgam thus formed to said distillation zone.

9. A process for reducing ore and distilling carbonaceous material which comprises introducing the carbonaceous material to a heating zone maintained at progressively increasing temperatures from the inlet end to the outlet end thereof, dist-illing volatiles from the carbonaceous material in an initial 

